The present invention relates to water treatment, and in particular to a method and apparatus for remediating wastewater holding areas and the like.
There have been developed over the years many different systems and devices for remediating wastewater holding areas, such as lagoons, ponds, holding vessels, basins, and other similar structures. Because of ecological considerations, research and development for feasible and economical solutions for cleaning up or remediating wastewater and other types of contaminated water have been greatly accelerated.
The modern treatment of domestic wastewater through biological means results in a residual byproduct comprised mostly of bacterial cell material and inert debris. A common practice in the treatment of domestic wastewater is to utilize large holding vessels, also known as lagoons, to provide the necessary detention time and environmental conditions to complete the treatment process. Clear liquid effluent is decanted from the treatment zone on a periodic basis, thereby leaving solid residuals as a settled sludge in the lower portion of the lagoon. Over time, the sludge accumulates, necessitating periodic removal. The sludge, which typically settles at the bottom of the lagoon, does not normally behave as a fluid, but rather resembles a heavy viscous or soft gelatinous material. It has been found that when a conventional pump is used to remove sludge from a retention area, the pump normally removes only a small area or portion of the sludge, such that complete remediation of the lagoon is difficult due to the unique characteristics of the sludge.
A number of different approaches have been utilized in the prior art for remediating wastewater holding areas and/or dewatering sludge. One such method comprises removing the surface water from the lagoon and dewatering the sludge through evaporation on an open drying bed prior to removal to a dumpsite. However, such processes are relatively invasive, and not environmentally sensitive to the adjacent area. Furthermore, the remediation process removes the lagoon from service, and undesirable odors often result from the long drying process, which typically requires turning over the sludge to achieve additional drying. Such methods also are not particularly effective in thoroughly drying the sludge to achieve a minimum volume, so as to facilitate removal and deposit of the dewatered sludge.
Other prior art dewatering sludge processes include utilizing belt presses, filter presses, centrifuges and sludge drying beds. The various sludge press and centrifuge systems are expensive to purchase, operate and maintain.
Consequently, a need exists for a cost effective, environmentally sensitive technique to remediate wastewater holding areas and the like in a non-intrusive manner, while keeping the lagoon in service.